What causes gamma ray bursts?
They come from huge explosions or collisions.
There are several different theories regarding what causes gamma ray bursts, but they focus around large amounts of energy being released from a huge explosion or collision.
The most commonly quoted theory is that they are the result of a black hole forming from a super massive star dying to form a supernova and then collapsing in on itself - an explosion that creates lots of high energy radiation.
It is also thought they could be from two incredibly dense neutron stars (another product of a stars death where the mass is compressed) colliding.
The reason gamma rays are released in these huge explosions (supernovae, colliding stars and nuclear bombs) is that they are such a high frequency, high energy wave - it needs to be a big explosion to have enough energy to form those waves.
Interestingly, gamma rays were first detected in the 1960's by scientists who were searching for gamma rays that would signal a violation of the Nuclear Test Ban Treaty signed during the cold war.
I hope this helps; let me know if I can do anything else:)
Electrical discharges in a normal star causes Gamma Ray Bursts, and has nothing to do with black holes compressing matter or neutron stars.
"The signal (gamma ray burst) comes from a normal star, where there's discharges in the magnetosphere which causes these ringing pulses to be sent out from a star; it has nothing to do with a lighthouse or spinning super-condensed object [i.e. neutron star]. I think the astrophysicists continually get into trouble by postulating states of matter and also the behavior of matter, which cannot be observed in the laboratory." -- Wal Thornhill